Update timer docs

[florian-h05]

This improves the docs for actions.ScriptExecution Timers by explaining how to pass variables to the callback function.

[florian-h05]

@rkoshak
Would be nice if you could have a quick look at the docs changes.

[rkoshak]

It looks good to me. The only thing I would add is the generic case of just passing one local variable to the timer instead of this. Theoretically (I've never done it though) that too would fix the variable same as the function generator does. But you can only pass the one variable.

[florian-h05]

The only thing I would add is the generic case of just passing one local variable to the timer instead of this.

That‘s possible, but …

that too would fix the variable same as the function generator does. But you can only pass the one variable.

I expect that it is not the same as with the function generator, I think you can mutate the var after the creation of the timer.
I have to test this to check my assumption.

I will modify the docs to have two ways of passing a var to a timer, both ways support this. The main difference should be that in one case the var can be changed after timer creation.

[florian-h05]

@rkoshak
Ready for re-review.

[rkoshak]

Just the one addition to add a comment explaining what happens when you change myVariable to "Hello mutation!".

[rkoshak]

Once that comment is added I think this is good to go.